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Medical Isotope Production without Highly Enriched Uranium
producers. Moreover, the Argentine organization CNEA has demonstrated that the alkaline process can be used with LEU targets, and work is underway (see Chapter 7) to develop an improved acid dissolution process for LEU targets. As discussed elsewhere in this report (see Chapter 10), the committee sees no technical barriers to adapting either of these processes for LEU-based Mo-99 production.
However, each of these processes has inherent advantages and disadvantages.17 For example, alkaline processing produces very pure Mo-99, solid waste that is suitable for storage, and fission gases that can be readily isolated for sale or for storage to allow for decay. On the other hand, relative to the acid process, alkaline processing produces larger volumes18 of processing solutions, it can require more time than the acidic process for target dissolution, and Mo-99 yields can be lower because some molybdenum may be incorporated into the solid residue. Additionally, hydrogen gas is produced in the alkaline process, which requires additional safety procedures.
Acidic processing, in contrast, generally requires shorter processing times, produces smaller volumes of processing waste, and results in slightly higher Mo-99 yields. On the other hand, additional steps have to be carried out to separate the Mo-99 from the processing solutions, and there needs to be a separate process for handling the treatment of the nitrogen oxide gases given off from the process.
These characteristics should only be viewed as generalities. All of the major producers have optimized their processing systems over many years to improve processing times, enhance recovery efficiencies, and minimize the production of liquid and solid waste.
A review of both alkaline and acid dissolution processes was provided by George Vandegrift (Argonne National Laboratory) during a presentation to the Committee in 2007.
The operative word here is “relative” because the liquid volumes are small (typically of the order of one or a few liters per processing batch) for either process.